docs: def _compute_focal_depth_term(self, C, rup):
          """
          Computes the hypocentral depth scaling term - as indicated by
          equation (3)
          """
          if rup.hypo_depth > 120.0:
              z_h = 120.0
          else:
              z_h = rup.hypo_depth
          return C['theta11'] * (z_h - 60.)